The friction characteristics of rock damage plane have important impact on the stability of block structure formed after the stratum is broken. The mechanics properties of rock damage plane are described by parameters...The friction characteristics of rock damage plane have important impact on the stability of block structure formed after the stratum is broken. The mechanics properties of rock damage plane are described by parameters such as roughness coefficient, wall compress strength and basic friction angle. These three coefficients for fine grain sandstone and medium granular sandstone and grit sandstone are test. The friction stress is researched at the condition of different normal compressive stress acting on the tension damage plane. The friction law of tension damage plane of sandstone abided by is summed up. This law will provide scientific basis for block structure stability judging in basic roof stratum and roof pressure intensity calculating.展开更多
This paper presents a new algorithm to predict locations and severities of damage in structures by changing modal parameters. An existing algorithm of damage detection is reviewed and the new algorithm is formulated t...This paper presents a new algorithm to predict locations and severities of damage in structures by changing modal parameters. An existing algorithm of damage detection is reviewed and the new algorithm is formulated to improve the accuracy of damage locating and severity estimation by eliminating the erratic assumptions and limits in the existing algorithm. The damage prediction accuracy is numerically assessed for each algorithm when applied to a two-dimensional frame structure for which pre-damage and post-damage modal parameters are available for only a few modes of vibration. The analysis results illustrate the improved accuracy of the new algorithm when compared to the existing algorithm.展开更多
According to the characteristics of deep engineering surrounding rock main shaft of No.3 mining district in Jinchuan, electron microscope scanning and rock mechanics test were adopted to analyze the damage features of...According to the characteristics of deep engineering surrounding rock main shaft of No.3 mining district in Jinchuan, electron microscope scanning and rock mechanics test were adopted to analyze the damage features of rock. The software of FLAG3D and Burgers body （Kelvin-Maxwell model） were used to research on rheological theory, and rheological model was modified. The results indicate that the damage of rock mass is very serious, and the rheological characteristics also outstanding; rheological behavior of deep surrounding rocks of the shaft can be taken as superposition of transient and stable rheology; and there exist the most dangerous zone on 100 m higher than 1 063 m level, so it is necessity that works of monitor and corresponding reinforcement should strengthen.展开更多
Non-specific arm pain is a special clinical condition that can occur in work-related activities that involve maintaining a static position for prolonged periods or repetitive and frequent movements of the hand or enti...Non-specific arm pain is a special clinical condition that can occur in work-related activities that involve maintaining a static position for prolonged periods or repetitive and frequent movements of the hand or entire arm. Such activities include typing on a keyboard, maneuvering a computer mouse, playing musical instruments （such as piano and guitar） and many forms of manual labor. The pain is dull and diffuse; It is localized in the forearm or in the hand but quickly can expand to the entire extremity. Non-specific arm pain is the most frequent type of work-related pain after lower-back pain. It thus has important socio-economic significance as a major cause of absence from work. The designation of ＂non-specific＂ originates from the fact that it has no obvious signs of tissue damage, unlike the ＂specific＂ pain accompanying carpal tunnel syndrome, tenosinovitis de Quervain, or lateral epicondylitis. Suggested causes of the pain include microtrauma of soft tissue followed by an inflammatory reaction, ischemia, fatigue, hyper-sensitization of nociceptors, focal dystonia of the hand and/or psychological stress. Treatment consists of application of NSAIDs, physical modalities, stretching and aerobic exercises. Prevention focuses on ergonomic modification during manual labor or work on a computer.展开更多
Objective ：To investigate the feasibility of using natural poritos as scaffolds in bone tissue engineering （TE） and repair of caprine mandibular segmental defect with titanium reticulum reinforced. Methods： Natur...Objective ：To investigate the feasibility of using natural poritos as scaffolds in bone tissue engineering （TE） and repair of caprine mandibular segmental defect with titanium reticulum reinforced. Methods： Natural poritos with a pore of 190-230 μm in size and porosity of about 50 %-65 % was molded into the shape of granules 5 mm × 5 mm × 5 mm in size. Expanded autologous caprine marrow mesenchymal stem cells were induced by recombinant human morphogenetic protein-2 （rhBMP2） to improve osteoblastic phenotype. Then marrow derived osteoblasts were seeded into poritos in density of 4 × 10^7/ml and incubated in vitro for 48 hours prior to implantation. Then osteoblastic cells/poritos complexes were implanted into mandibular defect and the defect was reinforced by titanium reticulum. Implantation of poritos alone acted as the control. Bone regeneration was assessed 4, 8, 16 weeks after implantation using roentgenographie analysis and histological observation was done after 16 weeks. Results： New bone could be observed histologically on the surface and in the pores of natural coral in all specimens in the cell-seeding group, whereas in the control group there was no evidence of osteogenesis process in the center of the construction. The results showed that new bone grafts were successfully restored 16 weeks after implantation. Conclusions： This study suggests the feasibility of using porous coral as scaffold material transplanted with marrow derived osteoblasts by TE method. By means of titanium reticulum reinforcement, mandibular defect could be successfully restored. It shows the potentiality of using this method for the reconstruction of bone defect in cfinic.展开更多
Objective： To construct tissue-engineered neural complex in vitro and study its effect in repairing acutely injured spinal cord in adult rats. Methods： Neural stem cells were harvested from the spinal cord of embry...Objective： To construct tissue-engineered neural complex in vitro and study its effect in repairing acutely injured spinal cord in adult rats. Methods： Neural stem cells were harvested from the spinal cord of embryo rats and propagated in vitro. Then the neural stem cells were seeded into polygiycolic acid scaffolds and co-cultured with extract of embryonic spinal cord in vitro. ce histochemistry and scanning electron microscope were used to observe the microstructure of this complex. Animal model of spine semi-transection was made and tissue-engineered neural complex was implanted by surgical intervention. Six weeks after transplantation, functional evaluation and histochemistry were applied to evaluate the functional recovery and anatomic reconstruction. Results： The tissue-engineered neural complex had a distinct structure, which contained neonatal neurons, oligodendrocytes and astrocytes. After tissue-engineered neural complex was implanted into the injured spinal cord, the cell components such as neurons, astrocytes and oligodendrocytes, could survive and keep on developing. The adult rats suffering from spinal cord injury got an obvious neurological recovery in motor skills. Conclusions： The tissue-engineered neural complex appears to have therapeutic effects on the functional recovery and anatomic reconstruction of the adult rats with spinal cord injury.展开更多
Objective： To analyze the management of high-voltage electrical burn injury of the scalp in our hospital. Methods： This study involved 10 patients who suf- fered from high-voltage electrical bum injury of the scalp...Objective： To analyze the management of high-voltage electrical burn injury of the scalp in our hospital. Methods： This study involved 10 patients who suf- fered from high-voltage electrical bum injury of the scalp. Scalp reconstruction was done by different modalities ac- cording to the size and location of the defect. Results： Complete flap viability was achieved in all the cases. We had one case of gapped wound which was managed only by dressing. Widening of the scar was found in 2 cases. Conclusion： Rotation, advancement and transposi- tion scalp flaps are used for reconstructing scalp defects caused by electrical bum. The choice of ideal flaps for re- construction depends upon the size and site of scalp defect.展开更多
文摘The friction characteristics of rock damage plane have important impact on the stability of block structure formed after the stratum is broken. The mechanics properties of rock damage plane are described by parameters such as roughness coefficient, wall compress strength and basic friction angle. These three coefficients for fine grain sandstone and medium granular sandstone and grit sandstone are test. The friction stress is researched at the condition of different normal compressive stress acting on the tension damage plane. The friction law of tension damage plane of sandstone abided by is summed up. This law will provide scientific basis for block structure stability judging in basic roof stratum and roof pressure intensity calculating.
基金The project was financially supported by the National Natural Science Foundation of China （No. 50479027）.
文摘This paper presents a new algorithm to predict locations and severities of damage in structures by changing modal parameters. An existing algorithm of damage detection is reviewed and the new algorithm is formulated to improve the accuracy of damage locating and severity estimation by eliminating the erratic assumptions and limits in the existing algorithm. The damage prediction accuracy is numerically assessed for each algorithm when applied to a two-dimensional frame structure for which pre-damage and post-damage modal parameters are available for only a few modes of vibration. The analysis results illustrate the improved accuracy of the new algorithm when compared to the existing algorithm.
基金Supported by the National Natural Science Foundation of China(50874042)Key Projects in the National Science & Technology Pillar Program in the Eleventh Five-Year Plan Period(2008BAB32B01)
文摘According to the characteristics of deep engineering surrounding rock main shaft of No.3 mining district in Jinchuan, electron microscope scanning and rock mechanics test were adopted to analyze the damage features of rock. The software of FLAG3D and Burgers body （Kelvin-Maxwell model） were used to research on rheological theory, and rheological model was modified. The results indicate that the damage of rock mass is very serious, and the rheological characteristics also outstanding; rheological behavior of deep surrounding rocks of the shaft can be taken as superposition of transient and stable rheology; and there exist the most dangerous zone on 100 m higher than 1 063 m level, so it is necessity that works of monitor and corresponding reinforcement should strengthen.
文摘Non-specific arm pain is a special clinical condition that can occur in work-related activities that involve maintaining a static position for prolonged periods or repetitive and frequent movements of the hand or entire arm. Such activities include typing on a keyboard, maneuvering a computer mouse, playing musical instruments （such as piano and guitar） and many forms of manual labor. The pain is dull and diffuse; It is localized in the forearm or in the hand but quickly can expand to the entire extremity. Non-specific arm pain is the most frequent type of work-related pain after lower-back pain. It thus has important socio-economic significance as a major cause of absence from work. The designation of ＂non-specific＂ originates from the fact that it has no obvious signs of tissue damage, unlike the ＂specific＂ pain accompanying carpal tunnel syndrome, tenosinovitis de Quervain, or lateral epicondylitis. Suggested causes of the pain include microtrauma of soft tissue followed by an inflammatory reaction, ischemia, fatigue, hyper-sensitization of nociceptors, focal dystonia of the hand and/or psychological stress. Treatment consists of application of NSAIDs, physical modalities, stretching and aerobic exercises. Prevention focuses on ergonomic modification during manual labor or work on a computer.
文摘Objective ：To investigate the feasibility of using natural poritos as scaffolds in bone tissue engineering （TE） and repair of caprine mandibular segmental defect with titanium reticulum reinforced. Methods： Natural poritos with a pore of 190-230 μm in size and porosity of about 50 %-65 % was molded into the shape of granules 5 mm × 5 mm × 5 mm in size. Expanded autologous caprine marrow mesenchymal stem cells were induced by recombinant human morphogenetic protein-2 （rhBMP2） to improve osteoblastic phenotype. Then marrow derived osteoblasts were seeded into poritos in density of 4 × 10^7/ml and incubated in vitro for 48 hours prior to implantation. Then osteoblastic cells/poritos complexes were implanted into mandibular defect and the defect was reinforced by titanium reticulum. Implantation of poritos alone acted as the control. Bone regeneration was assessed 4, 8, 16 weeks after implantation using roentgenographie analysis and histological observation was done after 16 weeks. Results： New bone could be observed histologically on the surface and in the pores of natural coral in all specimens in the cell-seeding group, whereas in the control group there was no evidence of osteogenesis process in the center of the construction. The results showed that new bone grafts were successfully restored 16 weeks after implantation. Conclusions： This study suggests the feasibility of using porous coral as scaffold material transplanted with marrow derived osteoblasts by TE method. By means of titanium reticulum reinforcement, mandibular defect could be successfully restored. It shows the potentiality of using this method for the reconstruction of bone defect in cfinic.
文摘Objective： To construct tissue-engineered neural complex in vitro and study its effect in repairing acutely injured spinal cord in adult rats. Methods： Neural stem cells were harvested from the spinal cord of embryo rats and propagated in vitro. Then the neural stem cells were seeded into polygiycolic acid scaffolds and co-cultured with extract of embryonic spinal cord in vitro. ce histochemistry and scanning electron microscope were used to observe the microstructure of this complex. Animal model of spine semi-transection was made and tissue-engineered neural complex was implanted by surgical intervention. Six weeks after transplantation, functional evaluation and histochemistry were applied to evaluate the functional recovery and anatomic reconstruction. Results： The tissue-engineered neural complex had a distinct structure, which contained neonatal neurons, oligodendrocytes and astrocytes. After tissue-engineered neural complex was implanted into the injured spinal cord, the cell components such as neurons, astrocytes and oligodendrocytes, could survive and keep on developing. The adult rats suffering from spinal cord injury got an obvious neurological recovery in motor skills. Conclusions： The tissue-engineered neural complex appears to have therapeutic effects on the functional recovery and anatomic reconstruction of the adult rats with spinal cord injury.
文摘Objective： To analyze the management of high-voltage electrical burn injury of the scalp in our hospital. Methods： This study involved 10 patients who suf- fered from high-voltage electrical bum injury of the scalp. Scalp reconstruction was done by different modalities ac- cording to the size and location of the defect. Results： Complete flap viability was achieved in all the cases. We had one case of gapped wound which was managed only by dressing. Widening of the scar was found in 2 cases. Conclusion： Rotation, advancement and transposi- tion scalp flaps are used for reconstructing scalp defects caused by electrical bum. The choice of ideal flaps for re- construction depends upon the size and site of scalp defect.
